Fiber Optical Cable and Connector System (FOCCoS) for PFS/Subaru

TL;DR

This paper describes the design, assembly, and testing of FOCCoS, a fiber optical system for Subaru Telescope that captures and transmits light to spectrographs with high precision and flexibility.

Contribution

It introduces a novel fiber optical cable and connector system with specialized assemblies and testing procedures for the Subaru Telescope's PFS instrument.

Findings

High throughput achieved in connection tests

Flexible fiber positioning within a 9.5mm patrol region

Successful assembly of 2400 fiber positioners

Abstract

FOCCoS, Fiber Optical Cable and Connector System, has the main function of capturing the direct light from the focal plane of Subaru Telescope using optical fibers, each one with a microlens in its tip, and conducting this light through a route containing connectors to a set of four spectrographs. The optical fiber cable is divided in 3 different segments called Cable A, Cable B and Cable C. Multi-fibers connectors assure precise connection among all optical fibers of the segments, providing flexibility for instrument changes. To assure strong and accurate connection, these sets are arranged inside two types of assemblies: the Tower Connector, for connection between Cable C and Cable B; and the Gang Connector, for connection between Cable B and Cable A. Throughput tests were made to evaluate the efficiency of the connections. A lifetime test connection is in progress. Cable C is installed inside the PFI, Prime Focus Instrument, where each fiber tip with a microlens is bonded to the end of the shaft of a 2-stage piezo-electric rotatory motor positioner; this assembly allows each fiber to be placed anywhere within its patrol region, which is 9.5mm diameter.. Each positioner uses a fiber arm to support the ferrule, the microlens, and the optical fiber. 2400 of these assemblies are arranged on a motor bench plate in a hexagonal-closed-packed disposition.